Origin of reduced magnetization and domain formation in small magnetite nanoparticles.

The structural, chemical, and magnetic properties of magnetite nanoparticles are compared. Aberration corrected scanning transmission electron microscopy reveals the prevalence of antiphase boundaries in nanoparticles that have significantly reduced magnetization, relative to the bulk. Atomistic magnetic modelling of nanoparticles with and without these defects reveals the origin of the reduced moment.

Ten-nanometer dense hole arrays generated by nanoparticle lithography.

Large area dense hole arrays with a feature size of ~10 nm were generated using self-assembled monolayers of nanoparticles as etch masks. To fabricate the hole arrays, monolayers of nanoparticles were irradiated by electron beam to turn surfactants into amorphous carbon, treated by acid to remove the nanoparticle cores, and then etched by CF(4) to deepen the holes. Evaporated gold films preferentially diffuse into the holes to generate gold nanoparticle arrays.